In business, you might use letters and memorandums to communicate with others. A letter contains the company’s letterhead or return address, the date, the recipient’s address, a subject line, salutation, message, closing and signature. A memo, by contrast, contains a date, subject line and a brief message but identifies the name of the sender and recipient without including addresses and is unsigned. Because of these differences, there are certain situations in which it is better to use a letter than a memo.

Mailed Communications

If you are writing to someone who is not an employee of your company, mail a letter rather than a memo. A letter includes the contact information the recipient may need to respond to you. The inclusion of an inside address, a salutation, closing and signature also makes a letter more formal and respectful for communicating with individuals outside of your company. A memo, on the other hand, does not include these elements and is better for communications within an office.

Privacy

Since a letter is folded, sealed in an envelope and individually addressed, it is a more private form of communication than a memo. For this reason, a letter might be used to submit a resignation or complaint to someone in the same company. A memo is used when privacy within an office is not a major consideration. For example, a memo might provide instructions to several people within the office who are working on a common project.

Major Announcements

Because letters are more formal than memos, they are also used to communicate major announcements. For example, if a business is announcing a merger, name change or new location, it might inform both its employees and individuals outside of the company with a letter. Since the letter will contain the company’s letterhead and contact information, it serves to further promote the company.

Analysis

A memo is brief and sticks to the facts. It is usually no more than a few paragraphs long and may be as short as a sentence or two. It provides instruction, information or results. A memo is not used to persuade the reader. If you wish to write an explanation or to convey reasons, arguments or analysis to your reader, use a letter. A letter can be longer than a memo and, since you will be signing the letter, is a proper forum for explaining your own analysis of a topic. For example, you might use a memo to inform your supervisor that sales were down by 10 percent in the past month, but use a letter to outline your analysis of the sales report and the reasons for the decrease.

About the Author

Janice Tingum has been writing professionally since 1979. She is the author of the biography "E.B. White: The Elements of a Writer" and her articles have appeared in “Lady’s Circle” and “Today’s Christian Woman” magazines. Tingum also paints and writes art instruction ebooks.